This invention relates to a seal lock and the like of the type incorporating a permanently secured single engagement, that is, when a bolt is inserted in a body, interengagement takes place therebetween and positively prevents removal of the bolt from the body without virtually complete destruction. According to certain of the principles of the present invention, the body includes a resiliently urged securement member mounted therein constantly urged into interference projecting partially into a bolt opening and retained in assembly prior to bolt insertion by a selectively movable plug within the bolt opening. A bolt end portion has a recess formed therein and when the bolt end portion is inserted into the body bolt opening, the plug is displaced inwardly of the body bolt opening permitting the body securement member to engage the bolt end portion and ultimately lodge in the bolt end portion recess permanently interengaging therein and positively preventing separation of the bolt and body. Various adjuncts may be incorporated into the structure for minimizing material requirements while preserving positive functioning and for eliminating the danger of possible tampering.
Various forms of seals have been previously used in years past at the access openings of shipping containers, for instance, at the access doors of trucks and railroad cars, and in many cases, in smaller sized shipping containers where the surreptitious removal of a portion of the contents thereof can present a problem. The prior seals have been of quite simple form and frequently have only consisted of a metal tape with a single enegement securement member, that is, a securement member of the type wherein, when the metal tape is engaged therewith, it is impossible to remove the same without a destruction of the tape or securement member. The prime purpose of these simple forms of seals as used on shipping containers has not been to secure the container against such unauthorized access, but has merely been for the purpose of indicating to the ultimate container recipient that such unauthorized access has been made.
In more recent times, the frequency of shipping container contents pilfering has become considerably more frequent. This has resulted in a new generation of various forms of seals which have rightfully been termed seal locks. As is denoted by the terminology used, these seal locks perform the prior function of the plain seals to denote that access to the contents of a shipping container has been obtained, and also to provide a reasonable degree of security in an effort to frustrate such violations, or at least delay or make more obvious the violation attempts so that the unauthorized persons involved and their attempts might be detected.
These seal locks approach and, in many cases, exceed the security of conventional key-type or combination-type locks, yet are of the single engagement, permanently secured form. Once these seal locks are engaged, it is intended that they cannot again be disengaged without virtual destruction of major portions thereof. Thus, in view of their single use, these seal locks must be of a relatively simple operating, permanently securing nature to minimize the cost thereof, while still being of a relatively high degree of security approaching, if not exceeding, the security of conventional key-type and combination-type locks.